A model is developed to study the long-term stability of monoatomic nanowires in terms of the nudged elastic band method and first-principles calculations. The model considers the elongation of a nanowire under a procedure that must be slow as compared with molecular motion. Test studies are performed for a simple system and excellent agreement is obtained when the theoretical predictions are compared with experimental results from the literature. (C) 2008 Elsevier B.V. All rights reserved.